The present invention relates to a process for converting aromatic compounds. More particularly, it is concerned with a process for combining an aromatic compound with a compound containing a double bond in the molecule by addition by the reuse of recycled iodine.
Processes for converting aryl compounds typically exemplified by Friedel-Crafts reaction in which an aromatic compound is reacted with an olefin in the presence of an acid catalyst are needed and important ones in chemical industry. Recently, the conversion processes by the use of a transition metal complex have called attention because of characteristics such as moderate reaction conditions, maintenance of unsaturation of the side chain in the converted aromatic compounds and other advantages. Studies have been made on process for converting aromatic hydrocarbons by the reaction of a aryl halide and a variety of unsaturated compounds with a palladium catalyst. However, there is a need for improvement in the reaction in which the palladium as catalyst is required in an equimolar amount to the amount of the aryl halide. Heek et al. proposed that carboxylic acids and esters thereof are produced by the carbonylation of an aryl halide with carbon monoxide with a catalystic amount of palladium when a base is coexistent (J. Org. Chem., 39, 3318 (1974); J. Org. Chem. 39, 3327 (1974). Since then, important of the reaction has become more recognizable. According to this reaction, however, the iodine contained in iodoarene is consumed as an iodide which is a neutral salt when the reaction is completed. Consumption of expensive iodine in the form of a neutral salt is unfavorable from an industrial point of view.
In order that the reaction of iodoarene with a palladium catalyst is commercially valuable, repeated use or recycling of the iodine is essential.